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Fluorescence lifetimes and quantum yields featuring polycyclic aromatic hydrocarbons (PAHs) and other organics constituting pyrogenic carbon particulate matter (PM) are seldom measured. In this work, PM sampled in a fuel-rich ethylene flame was firstly separated in organic carbon (OC), soluble in dichloromethane, and refractory organic carbon (ROC), soluble in N-methyl pyrrolidinone, and then analyzed by size exclusion chromatography (SEC) coupled with online UV and fluorescence detection, and by offline fluorescence spectroscopy and mass spectrometry. It was found that three classes of differently light emitting carbon dots (CDs) could be bottom-up synthesized in the same flame system by selecting appropriately the residence time. Actually, OC presented blue fluorescence regardless the residence time, whereas ROC sampled at low and high residence time emitted fluorescence in the green (green CDs) and in the yellow (yellow CDs) region, respectively. The SEC molecular weight of all CDs presented similar trimodal distributions, centered around 300, 1000 and 10,000 u. For the first time fluorescence lifetimes and quantum yields of pyrogenic CD fractions were measured as additional parameters useful for discriminating the fluorescent components and inferring their structural properties, with the support of mass spectrometry. The different spectroscopic features of CDs could be associated to different compositional characteristics as the polydispersity of molecular components featuring blue CDs, opposed to the oligomer-like nature of green and yellow CDs. Pyrogenic CDs showed different fluorescence emission ranges, quantum yield and lifetimes, appealing for their possible applications in the fields of imaging, electronics and sensors.

Carbon particles are widely distributed in the atmospheric aerosol as they mainly originate from a large variety of combustion sources emitting from micrometer sized soot aggregates down to ultrafine nanosized particles. Carbon particulate affects Earth's energy balance by scattering and absorbing radiation and by modifying the amount and properties of clouds, consequently causing climate changes. Moreover, nanometric particles have harmful impact on human health, thus the control of their emission is fundamental to limit their detrimental effects. Internal combustion engines are a significant emission source of carbon particles, especially as regards road vehicles for which particle filters are required to meet the limit of number and mass particles established by environmental regulations. Soot oxidation is the process at the basis of the regeneration of the particulate filters. This work aims at getting insights into the structural evolution of soot during its oxidation through an experimental study combining thermal analysis and chemico-physical characterization. Soot was collected from a laminar premixed flame and subjected to thermogravimetric analysis to extract its kinetic parameters. The activation energy of soot sample was found to be within the range of values typically found for carbon black and soot. A programmed thermogravimetric analysis was performed and stopped at different values of mass loss in order to obtain samples, which are representative of different advancements of soot oxidation, starting from the raw unoxidized soot: at the beginning (M70, 70% mass remaining after oxidation), in the middle (M50, 50% mass remaining) and almost at the end of soot oxidation (M20, 20% mass remaining). Raman spectroscopy allowed studying the nanostructure of partially oxidized soot samples. The Raman analysis showed that the more amorphous soot fraction burns first, thereafter soot does not undergo any significant change in the aromatic layers composing its turbostratic structure. The specific surface area was evaluated through the Brunauer-Emmett-Teller (BET) method for raw soot and partially oxidized soot (M70) showing a remarkable increase of the surface area after the oxidation process. This indicates that oxidation, after having preferentially removed the organic part, behaves in a non-preferential way towards the soot particle, suggesting the occurrence of internal burning of the particles.

Transmission Electron Microscope (TEM) is the only diagnostic tool giving access to it. However, being a diffraction-based technique, TEM images only aromatic systems and thus, it is particularly useful to combine it with electron energy-loss spectroscopy (EELS), able to provide quantitative information about the relative abundance of sp3 and sp2 hybridized carbon. In this paper a method for the EELS spectrum analysis of carbonaceous materials recently developed for electron-irradiated graphite and glassy carbon composition analysis has been applied for the first time on soot samples, in order to test its performance in soot nanostructure study in combination with TEM.

The present work focuses on the quality of char and primary tar produced from fast pyrolysis of lignocellulosic biomasses in both nitrogen (N2) and carbon dioxide (CO2) atmosphere. Three biomasses are investigated: Walnut Shells, the richest in Lignin, Straw, the richest in Hemicellulose, Pinewood, the richest in Cellulose. Heat treatment has been carried out in a heated strip reactor (HSR) at 1573 and 2073 K with holding times of 3 s and heating rate of 104 K/s. The equipment allows quenching the volatiles as soon as they are emitted from the particles and collecting them for further chemical analyses. The char samples are also collected and analysed by thermogravimetric analysis in air. Primary tar produced from pyrolysis of Walnut shells results to be the richest in monosaccharides among the samples investigated. Surprisingly monosaccharides are scarce in the tar produced from Straw, despite its high content of Hemicelluloses. PAHs and high molecular weight tar are present in the primary products of all the biomasses investigated, but particularly in tar from Walnut Shells, the biomass with the largest lignin fraction. The chars of the three investigated biomasses appear to be all constituted by multiple components. After heat treatment in N2 at 1573 K, the most reactive char is the one obtained from Straw, and the least reactive is the Walnut Shells char. More severe heat treatment and the presence of CO2 in the atmosphere generate additional char components with both higher and lower reactivity. Altogether the quality of the pyrolysis products does not correlate with the content of Cellulosde/Hemicellulose/Lignin of the original biomasses.

L'obiettivo generale del WP3 è la realizzazione di un sistema ibrido in grado di combinare la tecnologia solare termica a concentrazione con la tecnologia di combustione, allo scopo di migliorare le prestazioni in termini di costo di esercizio e di emissioni inquinanti, rispetto ad un sistema di combustione puro a combustibili fossili. A valle delle attività svolte nel corso del PAR 2015, che hanno visto l'individuazione, attraverso una campagna di misure sperimentali e mediante simulazione numerica, delle condizioni operative ottimali del sistema di combustione ibrido che utilizza la radiazione solare concentrata per aumentare l'entalpia del sistema mantenendo i livelli di emissione di inquinati al di sotto dei limiti di legge, si è proseguito nel corso del PAR 2016-2017 alla messa a punto del sistema combinato combustore-solare. L'obiettivo specifico per il PAR 2016-2017, quindi, ha riguardato la realizzazione di un modulo del sistema integrato combustore-solare su scala da laboratorio e dei relativi test di validazione.

Soot formation starts with particle nucleation, followed by mass and size growth through coalescence, coagulation, surface reactions, and finally by aggregation into fractal structures. The present work reports in deep detail the characteristics of carbon particulate produced at the inception in a heavily sooting laminar premixed ethylene flame. The cold gas velocity was enough low (to slower soot particle formation kinetics and thereby to widen the inception phase.

Diesel engine exhausts were analyzed downstream of a diesel particulate filter (DPF) and a selective catalytic reactor (SCR) to verify their effect on carbon particulate matter. An array of chemical, physical and spectroscopic techniques (Gas chromatography coupled with mass spectrometry (GC-MS), mobility analyzer, UV-visible absorption and fluorescence spectroscopy) was applied for characterizing the organic particulate matter (PM, constituted of polycyclic aromatic hydrocarbons (PAH), heavy aromatic compounds, soot) in the exhaust. The engine was operated in "half-load" (50% of the accelerator pedal position, representing the more common condition for engine in urban traffic) and "full-load" (100% of the accelerator pedal position, representing the best performance of the engine operation) conditions, at the same engine speed (2000 rpm). In "half-load" condition, soot formation is enhanced with respect to "full-load" one, but it was found that in this last condition the after-treatment systems are less efficient in the soot abatement just due to the much lower soot amount . Indeed, soot concentration in the exhaust after the DPF was about 40% higher in the "full-load" condition with respect to "half-load", and did not undergo any significant further concentration decrease after SCR, in both conditions. By contrast, PAH concentration after DPF was found to be much higher in the "half-load" (3 times) with respect to "full-load" and a further decrease of about 30% was found after the SCR. Also the heavy aromatic compounds, with molecular weights over the detectability range of GC-MS (300 u), were mitigated by SCR. Therefore, SCR resulted not effective in causing a further soot reduction, whereas it was able to largely reduce PAH and heavy aromatics emissions, especially in a lower temperature condition, when combustion efficiency is worse, as in the "half-load" case. Moreover, SCR system seems to support an agglomeration of particles, with beneficial effect on the harmfulness to human health.

The present work focuses on the effects of pressure on the quality of char and primary tar produced from fast pyrolysis of lignocellulosic biomass. Heat treatment has been carried out in a heated strip reactor (HSR) at 1573 K in nitrogen at 2, 4, 8 bar, with holding times of 3 s and heating rate of 104 K/s. The equipment allows quenching the volatiles as soon as they are emitted from the particles and collecting them for further chemical analyses. The char samples are also collected for thermogravimetric analysis in air. The DTG curves in air of char prepared at 2 bar shows two resolved peaks. Increasing the pressure of heat treatment from 2 to 4 bar has a minor effect on char reactivity, whereas further increase to 8 bar drastically changes the char combustion patterns, and the DTG curves exhibit only one well defined peak. For all the process conditions investigated, Oxo-aromatics are the dominant species in the tar. Benzendiol prevails in the 2 bar tar, followed by oxo-aromatic compounds related to lignin structure, while PAHs are mainly present as Fluorene. When pressure increases, Phenols compounds drastically prevail, and PAHs as Anthracene and Pyrene appear.

With the development of powerful diagnostics for deriving nanostructural parameters of carbons by both spectroscopic tools and imaging at nanometric level, it has been shown that soot nanostructure depends on its formation chemistry, i.e. on the hydrocarbon environment in which it is formed. Beside to combustion parameters as C/O feed ratio and temperature, the hydrocarbon environment in combustion processeis determined by the fuel molecule identity, As soot structure also affects soot oxidation reactivity in this work the effect of fuel on soot nanostructure and then on soot reactivity has been studied in flames of prototypical hydrocarbon fuels as methane, ethylene and benzene.

The present work reports about the laser-induced modifications undergone by a typical turbostratic carbon material as soot, formed at the first inception stage (nascent) and final maturation degree (mature) in different premixed flames. The structural modifications induced by laser heating were studied by advanced HRTEM imaging, provided the detailed characterization of the carbon network of pristine soot carried out by HRTEM, Raman, UV-Vis absorption and electron energy loss spectroscopy (EELS) [1,2]. The laser induced modifications resulted to be nanostructure-sensitive producing structures in form of "rosette" and void shells in the case of mature and coalesced amorphous material, respectively. These structures are observable in Fig. 1, where HRTEM images of nascent and mature ethylene soot before and after laser heating treatment are reported. The sensitivity to nanostructure is promising for developing laser heating as a structural diagnostic tool for carbon materials, but just such sensitivity has to be carefully considered when the laser is employed for diagnostic purposes.

In the present work fast pyrolysis of coal in N2 and CO2 atmospheres was studied using two different systems: a drop tube reactor (DTR) and a heated strip reactor (HSR). The two systems allow comparable particles heating rates with different temperature of the gas phase. The tars produced in the two systems have been analyzed with the aim to study the role of gas tar reactions in soot inception. It was found that in DTR, where volatiles react in a hot atmosphere, polycyclic aromatic hydrocarbons (PAH) formation and growth is larger than in the HSR, where the volatile species are quickly quenched. The results provide evidence that secondary reactions of the tar are a source of PAH, which in turn, can be soot precursors, even in pyrolytic conditions. Also soot formation is highly limited in the HSR system, confirming the role of tar in soot formation mechanism. The effect of CO2 is not straightforward and varies according to pyrolysis time and temperature.

Previous studies have addressed the effects of carbon dioxide (CO2) rich atmospheres, as those established in oxy-firing of solid fuels, on the properties of chars produced from pyrolysis of biomass. The present work complements previous investigation with experiments carried out under high heating rate/high temperature conditions in a purposely designed heated strip reactor (HSR). Walnut shell samples have been heat treated in the HSR in N2 and CO2 at temperatures of 1573-2073 K with holding times of 3s. Primary tar has been analyzed by GC-MS, char has been analyzed by thermogravimetric analysis and Raman spectroscopy. The effect of substitution of N2 with CO2 during heat up of biomass is not straightforward, as it can result in either an enhancement or reduction of char reactivity and structural order depending on the temperature. At 1573 K, CO2 chars are less reactive and more graphitized than N2 chars. In contrast, when the temperature is increased to 2073 K, CO2 chars turn out to be more porous, less graphitized and more reactive than N2 chars. The behavior is discussed within the frame of the competition of pyrolysis, gasification and thermal annealing.

Soot nanostructure was analyzed in fuel-rich premixed laminar C2H4/O2 flames at a constant C/O ratio of 0.8 and different maximum temperatures, namely 1620K and 1690K, obtained using different cold gas velocity. Bulk properties of soot as H/C ratio and reactivity were investigated, along with morphological, nanostructural and chemical features (using TEM, HRTEM, EELS). It was found that dehydrogenation and aromatization of soot occurring along the flames, are favoured at higher flame temperatures. Nevertheless, soot from the two flames reach a final nanostructure rather similar, independently on the temperature conditions at least in the 1620-1690K range.

La modellazione numerica di un sistema ibrido combustore e radiazione solare concentrata è di basilare importanza per la valutazione degli effetti della radiazione solare concentrata sull'aumento della potenza termica prodotta dal sistema di combustione, sulla struttura di fiamma e sulla formazione di inquinanti ai fini delle valutazioni preliminari alla progettazione del sistema. Il modello numerico utilizzato è stato sviluppato dall'unità DICMAPI- UNINA e consiste in un modello fluidodinamico con l'accoppiamento delle cinetiche di combustione per la predizione dell'evoluzione del sistema, uno schema cinetico in grado di predire la formazione dei principali prodotti della combustione così come dei sottoprodotti gassosi e particellari e un modello di scambio termico radiativo in grado di tenere in conto della presenza della radiazione solare. L'IRC-CNR ha applicato tale modello per simulare un sistema ibrido costituito da un combustore (fiamma a diffusione) accoppiato con la radiazione solare concentrata al variare delle condizioni operative.

The characterization of soot generated in inverse diffusion flames (IDF) is meaningful for the study of soot formation, with particular regard to soot inception. Indeed, it has been found that IDF soot keeps on the features of incipient (young) soot particles as those formed in combustion systems as premixed and diffusion flames. This work regards a deeper characterization of carbon particulate collected from the exhaust of an ethylene IDF in comparison to young and mature soot sampled inside an ethylene premixed flame (PMXF). Elemental analysis, Raman and UV-Visible spectroscopy were carried out to evaluate soot aromaticity features. The comparison between soot from these two different flame configurations confirmed that IDF is a suitable source of young soot to be massively analyzed. The features of mature soot derived from laboratory scale flames resulted to be similar to those of soot emitted in practical combustion processes as diesel engines and coal pyrolysis.

Time-of-Flight (TOF) Mass Spectrometry is a powerful analytical technique, provided that an accurate calibration by standard molecules in the same m/z range of the analytes is performed. Calibration in a very large m/z range is a difficult task, particularly in studies focusing on the detection of high molecular weight clusters of different molecules or high molecular weight species.External calibration is the most common procedure used for TOF mass spectrometric analysis in the gas phase and, generally, the only available standards are made up of mixtures of noble gases, covering a small mass range for calibration, up to m/z 136 (higher mass isotope of xenon). In this work, an accurate calibration of a Molecular Beam Time-of Flight Mass Spectrometer (MB-TOFMS) is presented, based on the use of water clusters up to m/z 3000.The advantages of calibrating a MB-TOFMS with water clusters for the detection of analytes with masses above those of the traditional calibrants such as noble gases were quantitatively shown by statistical calculations. A comparison of the water cluster and noble gases calibration procedures in attributing the masses to a test mixture extending up to m/z 800 is also reported. In the case of the analysis of combustion products, another important feature of water cluster calibration was shown, that is the possibility of using them as "internal standard" directly formed from the combustion water, under suitable experimental conditions.The water clusters calibration of a MB-TOFMS gives rise to a ten-fold reduction in error compared to the traditional calibration with noble gases. The consequent improvement in mass accuracy in the calibration of a MB-TOFMS has important implications in various fields where detection of high molecular mass species is required. In combustion products analysis, it is also possible to obtain a new calibration spectrum before the acquisition of each spectrum, only modifying some operative conditions. Copyright © 2016 John WileySons, Ltd.

The aim of the present work is the production of nanocarbons with properties suitable for practical applications starting from sundry kinds of carbon materials restructured in mild conditions (temperature

The structural analysis of carbons formed by thermally-induced annealing of an anisotropic carbon as naphthalene pitch is presented in this work. Naphthalene pitch has been heated in a furnace in mild conditions (low pressure and temperature

In the present work, a method involving Fast Fourier Transform (FFT) analysis and a home-made software was applied for interpreting the mass spectra of complex PAH-laden samples derived from combustion systems and from heavy fossil fuels, thereby giving information on their composition. FFT analysis allows individuating periodicities that can indicate preferential growth routes and/or fragmentation patterns related to the chemical composition .The home-made software is able to sort large polycyclic aromatic hydrocarbons (LPAHs), which were found to be the major components in the complex mixtures, by their carbon number and double bond equivalence (DBE) number. Iso-abundance plots were introduced to sort and visualize the molecular constituents into different types based on the carbon and double bond equivalence (DBE) numbers .

Tars, typically derived from coal and heavy fuel processing or formed in combustion, are complex mixtures of organic species with aromatic and aliphatic functionalities spanning from few hundreds up to thousands of Da of molecular weight (MW). Many different diagnostics are required for their characterization, nevertheless the identification of single molecular components is not straightforward, and the speciation of the huge number of aromatic molecules is only partially effective avoiding reaching the complete map of the tar composition. In the present work a fractionation method based on low-vacuum heating has been preliminarily tested on synthetic mixtures of polycyclic aromatic hydrocarbons (PAH) presumed to be the basic aromatic moieties of tar components. The characterization of the separated components has been done to verify the operative conditions more favourable to an effective separation. The procedure has been also applied to a typical sample of combustion-formed tar and a synthetic pitch for tracing to their structure/composition.

RATIONALE: Time-of-Flight (TOF) Mass Spectrometry is a powerful analytical technique, provided that an accurate calibration by standard molecules in the same m/z range of the analytes is performed. Calibration in a very large m/z range is a difficult task, particularly in studies focusing on the detection of high molecular weight clusters of different molecules or high molecular weight species. METHODS: External calibration is the most common procedure used for TOF mass spectrometric analysis in the gas phase and, generally, the only available standards are made up of mixtures of noble gases, covering a small mass range for calibration, up to m/z 136 (higher mass isotope of xenon). In this work, an accurate calibration of a Molecular Beam Time-of Flight Mass Spectrometer (MB-TOFMS) is presented, based on the use of water clusters up to m/z 3000. RESULTS: The advantages of calibrating a MB-TOFMS with water clusters for the detection of analytes with masses above those of the traditional calibrants such as noble gases were quantitatively shown by statistical calculations. A comparison of the water cluster and noble gases calibration procedures in attributing the masses to a test mixture extending up to m/z 800 is also reported. In the case of the analysis of combustion products, another important feature of water cluster calibration was shown, that is the possibility of using them as "internal standard" directly formed from the combustion water, under suitable experimental conditions. CONCLUSIONS: The water clusters calibration of a MB-TOFMS gives rise to a ten-fold reduction in error compared to the traditional calibration with noble gases. The consequent improvement in mass accuracy in the calibration of a MB-TOFMS has important implications in various fields where detection of high molecular mass species is required. In combustion products analysis, it is also possible to obtain a new calibration spectrum before the acquisition of each spectrum, only modifying some operative conditions.

Mass spectrometry has currently achieved a mass resolution capable of discerning chemical composition and structure in complex mixtures. However, whatever is the mass spectrometric system used, complex mixtures produce spectra with a huge number of peaks which generally make difficult the data analysis. In the present work, a method involving Fast Fourier Transform (FFT) analysis and a home-made software was applied for interpreting the mass spectra of complex PAH-laden samples derived from combustion systems and from heavy fossil fuels, therby giving information on their composition. Large polycyclic aromatic hydrocarbons (LPAHs) were found to be the major components in the complex mixtures. Iso-abundance plots were introduced to sort and visualize the molecular constituents into different types based on the carbon and double bond equivalence (DBE) numbers. The differences between the different carbonaceous materials could be easily observed by comparing their isoabundance plots.

Fossil fuel-derived and synthesized pitches, consisting of a complex mixture of numerous aromatic hydrocarbons, are important resources of polycyclic aromatic hydrocarbons (PAH) that can be treated for the manufacturing of various carbon-based materials as graphite electrodes, carbon anodes, carbon fibers and composites fibers. The quality of the pitch-derived carbons is strictly dependent on the complex composition and properties of pitch precursors. Details on the PAH composition of parent pitches and the related soft interactions and assembly mechanism, are important for determining final pitch properties achieved after the heat treatment, typically involved in the production of carbon artefacts. Besides, pitches are readily available mixtures of large PAH which can be used in the place of purposely-synthesized individual PAH, as realistic models of the different nanosized sp2 domains featuring ordered and disordered carbon materials. The study of their chemical characteristics and spectroscopic features can hence be useful to infer the structural characteristics of sp2 nanostructures in disordered carbon materials. Large unsubstituted and substituted monomeric aromatic compounds, along with oligomeric systems where aromatic units can be connected by e.g. C-C single bonds (oligo-aryl type), -CH groups, ether bridges, are considered to be the basic constituents of both coal tar [1,2] and naphthalene-derived pitches [3]. As a consequence of their different source, coal tar pitch (CP) and naphthalene pitch (NP) have quite different properties as softening point, coke yield, etc., in spite of their similar H/C atomic ratio (around 0.5) and aromatic nature. In this work the comparative study of their properties was carried out by a multi-array analytical approach including heptane and toluene extractions. A detailed characterization of parent pitches and solvent separated fractions was performed. Composition and thermal behavior were analyzed by gas chromatography-mass spectrometry, size exclusion chromatography, thermogravimetry and laser desorption-mass spectrometry to compare the volatility and thermal stability in relation to their solubility and molecular weight distribution. Specific structural features were measured by infrared, UV-visible and fluorescence spectroscopy. The cross-check of the information obtained by different methodologies, picking up from each technique the most important information, was useful to deepen and validate the characterization of very structurally different large PAH systems featuring both pitches. The deep spectroscopic analysis used to get insights on structural features as aliphatic/aromatic hydrogen distribution and aromatic moieties allowed to differentiate between the class of ortho fused PAH, featuring CP, and the class of aromatic rylene moieties interspersed with aliphatic (mainly naphthenic) groups, which makes up NP.

In the context of searching for alternative sources of carbon materials this work concerns the study of the structure of carbon materials obtained by carbonization at low temperatures (

L'attività iniziale nell'ambito della linea 3.3.4 del presente progetto, interamente svolta in collaborazione con l'Istituto di Ricerche sulla Combustione del CNR di Napoli (IRC-CNR), ha riguardato lo studio delle caratteristiche che devono essere possedute da uno spettrometro di massa per consentire la rivelazione di IPA in linea. L'analisi delle condizioni d'uso e dei parametri che caratterizzano le prestazioni richieste, ha portato ad individuare alcune condizioni che risultano determinanti ai fini del progetto, in particolare: -possibilità di ottenere uno spettro corrispondente all'intero intervallo di masse di interesse in tempi estremamente ridotti, tali da consentire di seguire l'evoluzione temporale della concentrazione delle specie in esame anche in presenza di fenomeni non stazionari; -risoluzione sufficientemente elevata per la rivelazione e l'indentificazione degli IPA; -possibilità di realizzare uno strumento maneggevole e dal disegno meccanico relativamente semplice.

The analysis and characterization of flame-formed products (i.e. Polycyclic Aromatic Hydrocarbons (PAH) and soot) still represents a crucial point not only for a deepening of the knowledge on reaction pathways in flames, but also for the control and monitoring of air anthropogenic emissions due to their dangerous effect on human health and on the environment. Gas Chromatography coupled to Mass Spectrometry (GC-MS) is the analytical technique usually applied to aromatic compounds relevant in the combustion field for the qualitative and quantitative analysis of PAH, according to the UNICHIM 825/1988 and EPA (US Environmental Protection Agency) methods 8270D and 610. However, GC-MS technique is limited to the detection of PAH up to coronene (7 rings, 300 Da) and lacks in the detection of high molecular weight aromatic species (>300 Da), commonly present in complex matrixes generated from fuel-rich combustion systems [3]. This strict limitation is mainly due to the low volatility of heavy aromatic species [4], which hinders the sample vaporization necessary for the gas chromatographic analysis. Moreover, the quadrupole analyzer generally coupled with GC, presents an upper mass range limit of m/z 1000. In the present work, different kinds of ionization systems and mass analyzers for mass spectrometric techniques have been explored in order to test their potentiality in extending the detection range of combustion products analysis with respect to GC-MS. In particular, Atmospheric Pressure Photo-ionization-Mass Spectrometry (APPI-MS) and Laser Desorption Ionization-Time of Flight Mass Spectrometry (LDI-TOFMS) have been tested in the analysis of samples collected in a fuel-rich premixed flame of ethylene-oxygen.

Polycyclic aromatic hydrocarbons (PAH), formed from incomplete combustion of a wide range of combustion sources, are believed to be hazardous to human health and to be soot precursors. The current European legislation provides PAH monitoring from exhaust through timeconsuming sampling by condensation, washing by solvent, filtration and off-line mass spectrometric analysis. Continuous on-line measurement of PAH inside and at the exhaust of combustion systems is still challenging. This is due to the small concentrations and limited selectivity of available measurement methods. The development of on-line mass spectrometric analysis, such as flame-sampling Molecular-Beam Time of Flight Mass Spectrometry (MB-TOFMS), has enabled the selective and sensitive detection of PAH, since the expansion of the flame gases through a nozzle into a lower pressure region leads to the formation of a nearly collisionless molecular beam. In the past several years, substantial progress has been achieved by supplementing traditional electron ionization molecular-beam mass spectrometry (EI-MBMS) with isomer-specific measurements using photo-ionization (PI-MBMS). However the inherent characteristics of on-line sampling and laser ionization allow PAH identification and comparative profiles along the flame evaluation whereas prevent PAH quantitative determination. In this work a quantitative analysis of flame-formed PAH with a MB-TOFMS is proposed through a calibration made with off-line techniques. Flame products from a premixed atmospheric pressure ethylene/oxygen laminar flame just above the soot formation threshold have been collected for several hours and concurrently analyzed on-line with the MB-TOFMS apparatus. The collected samples were extracted in solvent and off-line analysed by conventional GC-MS for quantitative determination of PAH. The GC-MS undetectable fraction was moreover analysed by other off-line chemical and spectroscopic techniques. From the on-line mass spectra acquired, the total area of each flame species has been evaluated and related to its concentration obtained by means of GCMS, thus calibrating the MB-TOFMS apparatus. Moreover, a measure of the sensitivity of such experimental apparatus and a comparison with the common off-line, less sensitive and more time-expensive, GC-MS for PAH analysis is given.

s of the papers presented at the French and Italian Sections IFRF and The Combustion Institute

Direct molecular imaging of carbon structures is allowed by recent progresses in high resolution electron transmission microscopy (HR-TEM). Advanced procedures of image analysis have been set up in order to extract quantitative structural information describing the shape, size and orientation of graphene sheets and their distribution inside the carbon particle. The HR-TEM data gathered on soot formed in flames fueled by different hydrocarbons (ethylene, benzene) are critically reviewed in the present paper putting in evidence the potentialities and the drawbacks of current procedures of HR-TEM imaging analysis. Some intriguing differences in coherent domains organization (Basic Structural Units, BSU) of soot were found in dependence on the fuel, particle aging and temperature. The primary particles early formed at soot inception (young soot) in ethylene flames were found to consist mostly of non stacked short graphitic segments mixed with small nuclei of amorphous/disordered carbon material. These structures transformed during soot aging with the enhancement of the stacked units. Soot from aromatic fuels presented, already from the beginning, a larger presence of BSU and negligible amorphous carbon. Moreover, benzene soot nanostructure showed a significant radial variation and the presence of shell almost and/or completely closed of few nanometers. In spite of these visual observations, small differences in quantitative parameters featuring the BSU of different soot were observed. Indeed, only a slight increase of the layer length was observed whereas the spacing of the BSU layers appeared to be quite constant (0.38 nm) independently on the fuel, aging and temperature. A more evident decrease of the percentage of non-stacked layers (nsl) and the increase of fractional coverage were observed with soot aging in particular for aromatic fuels and higher flame temperatures. In the present paper the perspectives of new imaging analysis methods are analyzed for a more robust statistic of BSU parameters evaluation (as for example the effective spaces between fringes) taking into consideration the addition of two key parameters as tortuosity and curvature radius which account for the deviations from the planar shape of the graphene layers. These improvements open the way to more efficient insights on soot nanostructure analysis by HR-TEM.

A novel apparatus based on Time of Flight Mass Spectrometry (TOF-MS) was recently developed and successfully applied for the on-line analysis of combustion products from atmospheric pressure combustion systems. The main advantage of this apparatus is the possibility of real-time mass spectra detection of big molecules nominally up to thousands of mass units and therefore it is very promising for its application in soot precursors detection above the polycyclic aromatic hydrocarbons (PAH) masses. However, in order to detect masses in so high mass range, accurate calibration by standard molecules in similar mass ranges is necessary. In gas phase the only standards generally employed are constituted by gas noble mixtures, therefore arriving at 136 Da. In the present work the accurate calibration of TOF-MS system is presented by using water clusters formed by condensation of water vapor in the supersonic beam as it passes from the atmospheric to low pressure region of the source through an orifice. Water clusters up to 160 water molecules have been detected, therefore extending the calibration range up to more than 3000 Da, in the optimal operative conditions. More than the large detection extension, the other advantage of using water clusters for calibration is the possibility of regulating the operative conditions in order to form the clusters from combustion water. This can allow to calibrate the system for the analysis of combustion products before each set of measurements, without any necessity of changing the injection system for introducing external standard molecules.

Heavy liquid fossil fuels are complex mixtures and their physical and chemical composition and properties strongly vary depending on their origin and treatment. The use of these fuels is very limited since they pose several problems of managing, combustion efficiency and environmental impact. Due to the high oil prices, refineries worldwide are now looking for an eco-friendly and efficient processing and utilization of these heavy fuels. Detailed definitions of their composition and thermal properties are relevant for the fuel processing and managing in refinery and combustion plants. In this work, fractionated solvent extraction of heavy crude oil and coal- and petroleum-derived fuels was performed with solvents of different polarity as heptane, toluene and N-methyl-pyrrolidinone (NMP). The fractionated solvent extraction showed to be able for the isolation of classes with narrow molecular weight (MW) and chemical properties suitable to be analyzed in detail. The characterization of each solvent fraction was carried out by means of Size Exclusion Chromatography, infrared spectroscopy and thermogravimetry for determining their MW distribution, functional groups, volatility and reactivity. The extraction procedure and analytical methodology were tested and applied to typical combustible materials of different volatility and chemical complexity as a coal-pitch derived from the high-temperature coking of a coal, a Maya crude oil and an atmospheric residue from a sweet-crude oil, named syncrude. Overall, the characterization of the solvent fractions showed that the solvent affinity of heavy fuels is determined by both volatility and chemical characteristics. Heptane solubilize the fraction of heavy fuels containing aliphatic compounds and/or aromatics with aliphatic substituents volatilizing in a relatively low temperature range (from 150 to 400°C). The heptane insolubilization mainly pertains to the lower volatility fraction (from 300 and beyond 500°C) containing heavy aromatic/aliphatic species. Toluene solubilizes the lower-MW aromatic/aliphatic species contained in the heptane-insoluble residue as in the case of a crude oil and syncrude. The heavy aromatic species contained in the pitch are completely insoluble in toluene. Solubilization in NMP, poor for highly aliphatic species, is efficient for highly-aromatic volatile species as those contained in the heptane-insolubles of pitch.

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On-line detection of benzene and polycyclic aromatic hydrocarbons (PAH) has been performed by using a time of flight mass spectrometer (TOF-MS), which has been designed and implemented for obtaining in real time complete mass spectra from molecules of few mass units up to thousands of mass units (corresponding to nanometric dimensions). The flames have been fed with different C/O ratios under and above the soot formation threshold (C/O=0.66) but in any case well above the stoichiometric limit (C/O= 0,33). The combustion source used is a premixed laminar flame. The on-line transfer of combustion gases from atmospheric pressure to the high vacuum of a mass spectrometer has been performed by a combination of a steady sampling flow from the flame with a pulsed expansion into the ionization chamber of TOF-MS (molecular beam). The validation of the technique has been performed in this work by comparing the composition profiles of benzene and PAH measured by TOF-MS with those found in the literature evaluated by means of conventional analytical techniques based on gas chromatography (GC). The good agreement obtained with the literature suggests that the apparatus can be used for the on-line monitor of combustion systems. The high sensibility and fast response of the technique should allow the application also to practical complex sources such as exhausts from engines and from industrial plants for energy production and waste disposal beside to atmospheric aerosols. The mass spectrometric analysis moreover allows to detect and identify through the fragmentation paths more hydrocarbon species with respect to conventional techniques that can be useful for studying kinetic mechanism of pyrolitic reactions. Copyright © 2010, AIDIC Servizi S.ri.

Although many definitions of sustainable mobility exist, it is defined here as the capacity to meet the needs of society to move people and goods freely, communicate, trade and establish relationships while ensuring, at the same time, the preservation and conservation of basic human values, the physical environment, and natural and economic resources. A policy for the sustainable development of mobility must therefore evaluate and monitor the effects of mobility on human beings and, more generally, on the ecosystem, and, at the same time, consider its economic and social impact. The evaluation of sustainability is therefore based on the definition of indicators of environmental, economic and social impact. Italy's situation imposes the need to evaluate environmental impact not only on human beings, but also on the cultural heritage, which constitutes both a major economic resource and the foundations of our cultural identity.

Spectroscopic and microscopic features of soot generated from premixed sooting flames of aliphatic and aromatic fuels were analyzed in the soot inception region and in the zone of the completeness of soot formation process where mature soot is formed. A description of soot properties in terms of morphology, aromaticity and internal structure was obtained by means of a detailed Transmission Electron Microscopy (TEM) and chemical and spectroscopic analysis. The differences in the morphological structures of benzene and ethylene soot allowed to infer a correlation with the evolution of optical properties of soot.